This invention relates to a droplet ejection apparatus that ejects liquid supplied from a sub-tank as droplets. This invention is particularly effective when applied to an ink-jet recording apparatus (ink-jet printer).
When there is a bubble or a foreign body choked inside an ejection head of a droplet ejection apparatus, or a solid body or a slurry stuck to the ejection head, the droplet ejection apparatus is no longer able to eject droplets normally. The solid body or slurry here is a transformed body of an ingredient contained in liquid, which viscosity is increased by evaporation of moisture. Accordingly, an ink-jet recording apparatus including a droplet ejection apparatus, for example, is no longer able to obtain a favorable image (recording result).
To solve this problem, for example, an ink-jet recording apparatus includes a recovery function of a positive pressure purge system. In the ink-jet recording apparatus, the air inside the sub-tank is compressed using an air pump to apply pressure (positive pressure) to the ink inside the sub-tank. The pressure washes away the ink to the downstream so as to discharge the ink from the ejection head. In this manner, ink and foreign bodies inside the ejection head are removed.